/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.servlet.http;

import java.io.IOException;
import java.util.Arrays;
import java.util.Hashtable;
import java.util.ResourceBundle;
import java.util.StringTokenizer;

import javax.servlet.ServletInputStream;

/**
 * @deprecated As of Java(tm) Servlet API 2.3. These methods were only useful with the default encoding and have been
 *                 moved to the request interfaces.
 */
@SuppressWarnings("dep-ann") // Spec API does not use @Deprecated
public class HttpUtils {

    private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
    private static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);


    /**
     * Constructs an empty <code>HttpUtils</code> object.
     */
    public HttpUtils() {
        // NOOP
    }


    /**
     * Parses a query string passed from the client to the server and builds a <code>HashTable</code> object with
     * key-value pairs. The query string should be in the form of a string packaged by the GET or POST method, that is,
     * it should have key-value pairs in the form <i>key=value</i>, with each pair separated from the next by a &amp;
     * character.
     * <p>
     * A key can appear more than once in the query string with different values. However, the key appears only once in
     * the hashtable, with its value being an array of strings containing the multiple values sent by the query string.
     * <p>
     * The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to
     * spaces, and characters sent in hexadecimal notation (like <i>%xx</i>) are converted to ASCII characters.
     *
     * @param s a string containing the query to be parsed
     *
     * @return a <code>HashTable</code> object built from the parsed key-value pairs
     *
     * @exception IllegalArgumentException if the query string is invalid
     */
    public static Hashtable<String,String[]> parseQueryString(String s) {

        String valArray[] = null;

        if (s == null) {
            throw new IllegalArgumentException();
        }
        Hashtable<String,String[]> ht = new Hashtable<>();
        StringBuilder sb = new StringBuilder();
        StringTokenizer st = new StringTokenizer(s, "&");
        while (st.hasMoreTokens()) {
            String pair = st.nextToken();
            int pos = pair.indexOf('=');
            if (pos == -1) {
                // XXX
                // should give more detail about the illegal argument
                throw new IllegalArgumentException();
            }
            String key = parseName(pair.substring(0, pos), sb);
            String val = parseName(pair.substring(pos + 1), sb);
            if (ht.containsKey(key)) {
                String oldVals[] = ht.get(key);
                valArray = Arrays.copyOf(oldVals, oldVals.length + 1);
                valArray[oldVals.length] = val;
            } else {
                valArray = new String[1];
                valArray[0] = val;
            }
            ht.put(key, valArray);
        }
        return ht;
    }


    /**
     * Parses data from an HTML form that the client sends to the server using the HTTP POST method and the
     * <i>application/x-www-form-urlencoded</i> MIME type.
     * <p>
     * The data sent by the POST method contains key-value pairs. A key can appear more than once in the POST data with
     * different values. However, the key appears only once in the hashtable, with its value being an array of strings
     * containing the multiple values sent by the POST method.
     * <p>
     * The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to
     * spaces, and characters sent in hexadecimal notation (like <i>%xx</i>) are converted to ASCII characters.
     *
     * @param len an integer specifying the length, in characters, of the <code>ServletInputStream</code> object that is
     *                also passed to this method
     * @param in  the <code>ServletInputStream</code> object that contains the data sent from the client
     *
     * @return a <code>HashTable</code> object built from the parsed key-value pairs
     *
     * @exception IllegalArgumentException if the data sent by the POST method is invalid
     */
    public static Hashtable<String,String[]> parsePostData(int len, ServletInputStream in) {
        // XXX
        // should a length of 0 be an IllegalArgumentException

        // cheap hack to return an empty hash
        if (len <= 0) {
            return new Hashtable<>();
        }

        if (in == null) {
            throw new IllegalArgumentException();
        }

        // Make sure we read the entire POSTed body.
        byte[] postedBytes = new byte[len];
        try {
            int offset = 0;

            do {
                int inputLen = in.read(postedBytes, offset, len - offset);
                if (inputLen <= 0) {
                    String msg = lStrings.getString("err.io.short_read");
                    throw new IllegalArgumentException(msg);
                }
                offset += inputLen;
            } while ((len - offset) > 0);

        } catch (IOException e) {
            throw new IllegalArgumentException(e.getMessage(), e);
        }

        // XXX we shouldn't assume that the only kind of POST body
        // is FORM data encoded using ASCII or ISO Latin/1 ... or
        // that the body should always be treated as FORM data.
        try {
            String postedBody = new String(postedBytes, 0, len, "8859_1");
            return parseQueryString(postedBody);
        } catch (java.io.UnsupportedEncodingException e) {
            // XXX function should accept an encoding parameter & throw this
            // exception. Otherwise throw something expected.
            throw new IllegalArgumentException(e.getMessage(), e);
        }
    }


    /*
     * Parse a name in the query string.
     */
    private static String parseName(String s, StringBuilder sb) {
        sb.setLength(0);
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            switch (c) {
                case '+':
                    sb.append(' ');
                    break;
                case '%':
                    try {
                        sb.append((char) Integer.parseInt(s.substring(i + 1, i + 3), 16));
                        i += 2;
                    } catch (NumberFormatException e) {
                        // XXX
                        // need to be more specific about illegal arg
                        throw new IllegalArgumentException();
                    } catch (StringIndexOutOfBoundsException e) {
                        String rest = s.substring(i);
                        sb.append(rest);
                        if (rest.length() == 2) {
                            i++;
                        }
                    }

                    break;
                default:
                    sb.append(c);
                    break;
            }
        }
        return sb.toString();
    }


    /**
     * Reconstructs the URL the client used to make the request, using information in the
     * <code>HttpServletRequest</code> object. The returned URL contains a protocol, server name, port number, and
     * server path, but it does not include query string parameters.
     * <p>
     * Because this method returns a <code>StringBuffer</code>, not a string, you can modify the URL easily, for
     * example, to append query parameters.
     * <p>
     * This method is useful for creating redirect messages and for reporting errors.
     *
     * @param req a <code>HttpServletRequest</code> object containing the client's request
     *
     * @return a <code>StringBuffer</code> object containing the reconstructed URL
     */
    public static StringBuffer getRequestURL(HttpServletRequest req) {
        StringBuffer url = new StringBuffer();
        String scheme = req.getScheme();
        int port = req.getServerPort();
        String urlPath = req.getRequestURI();

        url.append(scheme); // http, https
        url.append("://");
        url.append(req.getServerName());
        if ((scheme.equals("http") && port != 80) || (scheme.equals("https") && port != 443)) {
            url.append(':');
            url.append(req.getServerPort());
        }

        url.append(urlPath);
        return url;
    }
}

